QUESTION: Is there a way you can make another probe that will last longer in Jupiter's atmosphere. ANSWER from Charlie Sobeck on February 23, 1996: The short answer to this question is *Yes!* The Galileo Probe was required to go down to a pressure of 10 bars, and in fact reached a level of 22 bars! In addition to discussing the possibility of probes into Saturn, Neptune and Uranus, scientists are already talking about the possibility of sending *deep probes* to these same planets as well as to Jupiter. These deep probe would descend to pressures of 100 bars or greater. But it is not likely to happen soon. Although such a probe could be built, it would not be a simple upgrade to the Galileo vehicle. It would be a major challenge, and the costs would be high. In addition to the increased pressure, such a deep probe would have to have a much better communications system, since it would be trying to transmit a signal through a MUCH thicker atmosphere. And the science instruments would probably be entirely different. The Galileo instruments were intended to measure the upper atmosphere, where the Sun's radiation plays a major role. Deeper in the atmosphere, the Sun is no longer an important contributor, and the scientific questions to be asked are significantly different. So, although such a deep probe mission is possible, it is likely that there will be other, higher priority missions to spend our money on first. But I don't think this will be our last trip to Jupiter! ANSWER from Charlie Sobeck on January 5, 1996: Actually, the technology on the Probe is more like 20 years old! It was launched 6 years ago, but it was essentially fully built by 1984, and most of the various parts were bought by 1979! Some thing could be improved (mostly the electronics), but much of it could not. For example, we could use much better computers if we could do it all over today. But we couldn't transmit any more data, because that's limited by the size of our antenna and the power in our batteries. The batteries used on the Probe were extremely good, and would not be much better today, and we couldn't use a bigger antenna because that would just make everything weigh more, and that would create a whole new set of problems. The same kind of arguments apply the the heat shield and parachute as well. What could we improve upon? Well, as I said, mostly the electronics. But how would that help if we couldn't transmit any more data? Mostly, the improvement would be in what the new electronics could do, how fast and how well. With better electronics we could make measurements more accurately, that would help. We could also do more computations on the spacecraft and send back only the answers, instead of sending back all the raw data and doing the computations on the ground, this would essentially allow us to compress the data, that would help too. And of course, with newer electronics everything would be smaller and lighter, so maybe we would be able to fly an extra battery or two. Certainly THAT would help! ANSWER from Dan Carlock on January 26, 1996: There's always the urge to make a product "newer" and "better", and an atmospheric entry probe is no exception. There are many candidates for design improvements; I have restrained myself to mentioning only four: 1. Smaller packaging. The Galileo Probe was built with mid-1970's technology which clearly is no longer the "state-of-the-art." Electronic and mechanical devices are available today which can accomplish the same tasks-- and often, much more-- with drastic reductions in size, weight, and power requirements. Kinda like the difference between early portable TV's which were bulky and weighed tens of pounds, and little solid-state, LCD screen TV's which weigh only ounces and fit in your coat pocket. 2. Higher-operating temperature electronics. Environmentally rugged, high-temperature metal-oxide semiconductors (HTMOS) which can work at temperatures far beyond the Galileo Probe's operational limits. For example, a typical operating temperature limit is 60 degrees Celsius. Electronics have been recently introducted which can operate to 225 degrees C, and development is underway to extend this limit to as high as 300 degrees C-- three times the temperature of boiling water on Earth at sea level! If such electronics were used in the Galileo Probe, it probably would have lasted longer. Of course, any new electronic components will still need to meet other stringent space requirements such as radiation hardening and low power consumption. 3. Faster, more powerful computer. Believe it or not, the Galileo Probe utilized independent 8-bit microprocessors with only kilobytes of memory each! By comparison, your school or home computer probably has a 16 or 32 bit microprocessor with Megabytes of memory-- capable of faster and far more complex calculations and operations for tasks the Probe must perform, like commanding, data acquisition and processing, and telemetry generation. If the Galileo Probe were built with such a computer today, the flight software-- the Probe's internal computer program-- could be improved by way of better self-testing (diagnostic capability) that would make it easier for us to check the Probe's health, or even allow it to "fix" itself. Other benefits would include more sophisticated algorithms to handle events like the tricky parachute deployment, and more straightforward time-tagging of the telemetry data. 4. Better Ground Cooling. During testing on Earth, testing sometimes had to be cut short because the Probe had a tendancy to overheat! Provision of cooling ports and ducting, and associated support equipment-- like cooling units used for aircraft while they remain parked at the gate-- would have enabled us to test the Probe longer without fear of overheating and damaging its electronics.